12/13/2016

1

Binder Modification to soften Grades

John D’Angelo

D’Angelo Consulting, LLC

johndangelo@dangeloconsultingllc.com

Demand for soft grades of

Binder

There is an increased demand for softer grade asphalt binders such as PG 58-28, 52-34 . Increased RAP usage

Use of RAS

Increased demand for improved low temperature grades to reduce cracking.

Limits on the availability of crudes to produce softer grade straight binders.

12/13/2016

2

Definition - Asphalt

A high molecular weight, thermoplastic hydrocarbon constituent, found in a large number of petroleum crude oils. Although some asphalts do occur naturally, asphalt as we know it, and as discussed herein, is derived from fractional distillation of petroleum crude oil.

-4-

Flow diagram for typical refinery

12/13/2016

3

UTI of Performance Grade Asphalts

A PG 64-22 would have a UTI of 86 C°

A PG 58-28 also has a UTI of 86 C°

If we needed a PG 76-22, which has a UTI of 98 C° -how is this accomplished?

As a “rule of thumb”, to achieve a UTI of >92 C°, or 86 C° V or E Grade MSCR the asphalt has to be

“modified”.

Depending on crude source, some binders with more narrow UTI’s of 86 and 89 C° may also require modification

40

46

52

58

64

70

76

82

-46 -40 -34 -28 -22 -16 -10

Tmin, °C

Tm

ax

, °C

soft

hardCrude ABC PG Line

425C

V

D

U

350C

V

D

U

For a given crude, asphalt grade is defined by refinery processing conditions

Puzic 2005

12/13/2016

4

Refining Crude Oils

Refinery output driven by

Crude source

Refinery configuration

Economics

Crude Oil

Different crude oils will produce different asphalt binders with different properties.

12/13/2016

5

Grading System

Based on Climate

PG 58-28

PerformanceGrade

Accumulated days of high pavement

design temp

Min pavementdesign temp

Grading System

Based on Climate

PG 58-28

PerformanceGrade

Accumulated days of high pavement

design temp

Min pavementdesign temp

Changing the low Temperature Grade is

very difficult

12/13/2016

6

Softening agents

There are limited ways to produce asphalt binder with lower, low temperature grades.

Heavy Vacuum Gas Oils

Tall Oils

Aromatic Oils

Recycled Oils

Bio Oils

Most are expensive and have limited effect

Component makeup of the 2

asphalt binders

Property Test Method AC 1 AC 2

Basic Composition: As Received

Ash, % AASHTO T 111 0.04 0.06

Solubility, % ASTM D 2042 99.98 99.94

Component

Fractions, %

Asphaltenes

ASTM D 4124,

SARA Fractions

by Iatroscan

14.9 14.2

Polar Aromatics 39.7 39.7

Naphthene

Aromatics34.6 36.9

Saturates 10.8 9.9

12/13/2016

7

Change in SARA with aging and RAP

Recovered Binder after APWS N70 RAP Mix

12/13/2016

8

VTAE affects on binder grade and aging

Lab Blends %

AASHTO M 320, Table 1, PG continuous grade & Difference

between S and m grade temperature

0 2 4 6 8 20

PG 64-22 1 w/VTAE 1 67.3-26.2 68.3-25.0 64.9-26.5 64.2-27.6 62.6-26.5 55.6-26.6

Difference Between S &

m grade-1.5 -4.6 -3.6 -3.7 -6.9 -15.2

PG 64-22 1 w/VTAE 2 65.9-24.8 66.0-25.7 65.6-25.9 64.9-27.6 61.5-26.0

Difference Between S &

m grade2.2 -4.6 -5.7 -4.5 -9.8

PG 64-22 2 w/VTAE 1 66.5-25.9 64.7-26.7 63.9-27.2 62.6-28.1 61.0-27.4 55.8-29.8

Difference Between S &

m grade0.2 -0.5 -1.8 -2.5 -4.8 -7.9

PG 64-22 2 w/VTAE 2 65.5-26.0 64.3-27.1 63.9-27.7 63.3-27.3 60.1-31.0

Difference Between S &

m grade-3.7 -4.3 -5.7 -4.5 -12.1

Blends Continuous GradesOriginal and Recovered

PROPERTY

RESULTS Recovered Binder

Mix with 5% RAS

0.5% Antistrip:

Control VTAE

8% 16% 24%

AASHTO M 320 SUPERPAVE™ Binder Grade, PG:

76-16 70-22 70-22 70-22

Continuous Grade 79.7-21.4 74.3-24.8 73.8-23.2 74.4-23.6

Difference Between S & m grade -4.3 -5.4 -12.6 -14.4

Lab Blends %

AASHTO M 320, Table 1, PG continuous grade & Difference between S and m grade

temperature

Control 6% VTAE6% VTAE &

0.5% AS10% VTAE

AASHTO M 320 SUPERPAVE™ Binder Grade, PG:

64-22 58-22 58-22 58-28

True Grade66.2-25.61

62.0-27.45

61.2-29.09 59.8-28.83

Difference Between S & m grade 2.3 -1.2 -1.5 -3.3

12/13/2016

9

Study Walaa Mogawer UMass

Glover Rowe Cracking Criteria

12/13/2016

10

SCB I Fit 64-28

TTI NCHRP 9-58 RA Dosage Selection Overall G-R Results

Target Binder ≤ Recycled Blends @ opt RA < Recycled Blend no RA

Error bar: standard deviation of 2

replicates

1

10

100

1000

10000

Target Binder

70-22

Control

64-22

No RA

Recycled

64-22

4.5% T1

Recycled

64-22

5.5% A1

Glo

ver

-Row

e P

ara

met

er (

kP

a)

Blend

0.3 RBR (0.1 RAP & 0.2 RAS)

RTFO PAV-20 PAV-40

12/13/2016

11

TTI NCHRP 9-58RA Dosage Selection – Mixture Validation - SCB

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

Target RecycledControl

Recycledw/T1 @ FLD

(2.7%)

Recycledw/T1 @ FLD

(64-28)

Recycledw/T1 @(3.5%)

Recycledw/T1 @ OPT

(4.5%)

Recycledw/A1 @ OPT

(5.5%)

Recycledw/T1 @ OPT

(TOAS)

Fle

xib

ilit

y I

nd

ex

(F

I)

STOA LTOA

Summary

Producing Softer PG binders generally not economical.

Multiple additives available to soften binders.

Each has advantages and limitations.

Significant Engineering is needed to optimize performance.

12/13/2016

12

Thank You!